Backup web servers? How does it default?

[Keegan]

Hey all,

I have a brand new beautiful web server installed at work. But what we want to do is to also have a backup web server at a different site that uses a different provider. What i can't figure out is how to set this up. I dont think i can do it through DNS. By providing two IP's, DNS servers randomly pick one, not neccessarily the one that is active.

My only thought on how to do this is as follows:
The main access to this web server is through a link on another server. My thought is to have a script that runs when the link is clicked that pings the main server to see if it is active, and if not, routes the user to the backup. I'm sure that if this is a reasonable solution then it has been done in the past. Anyone have any ideas as to where i could find something like this?

Any other ideas would be very helpful.

Thanks,
Keegan

 

[goldboyd]

While I have never configured a backup webserver offsite, nor do I know how to do it sucsessuflly, I do have a few comments

The main problem with your current idea is that it still leaves a single point of failure. If the server that chooses which server to go to goes down, so does your web site, even if your 2 web servers are up and functioning properly. Also having to attempt to ping the server each time the site is accessed, that will cause delay, network overhead...

Having 2 clustered servers in one location would be a lot easier to setup, as depending on the OS it might have support built in, or you could write some fancy unix scripts to take car of the job also. Or you could use some type of load balancer in front of them. But this is not quite as reliable as 2 servers in different locations, I would assume.

I know that wasn't really an answer to your question, but hopefully it's a start.

 

[Russ]

Load balancers are mighty expensive. You might take a look at the Linux virtual server project. I've never done anything like this since I have no need to, but it is what AnandTech is using to balance the load between it's servers.

Russ, NCNE

 

[Keegan]

Well, to clarify the proposed solution:

On the website that links to the new webserver, there would be two links. One to the main server and one to the backup. There would be a note saying that if there was no response from the main server to use the backup. What we want to prevent is users using the backup if the main site is up. Therefore a script would run when the backup server was selected that would ping the main server and if up re-route to that. Otherwise it would load the backup..

Sorry, i know its a bit complicated but i would really appreciate feedback.